SIM: undesired connections by mxdomainmgr.exe

Hi all.

I have running a Server-Software (like Telnet)listening on Port 8000. I have started this program on 5 Computers. After a while I seeon each Computer a connetion by the mxdomainmgr.Why makes mxdomainmgr connections to ohter computers on Port 8000 ?What can I do to prevent this undesired connections by mxdomainmgr.exe.